Crosslinking of cellulosic materials with products produced by the reaction of alkyl sulfonamides and formaldehyde under alkaline conditions

ABSTRACT

Formaldehyde is reacted with alkyl sulfonamides under alkaline conditions. The resulting products are useful modification agents for cellulosic fibers.

United States Patent Inventors Ronald Swidler CROSSLINKING OF CELLULOSIC MATERIALS WITH PRODUCTS PRODUCED BY THE REACTION OF ALKYL SULFONAMIDES AND FORMALDEI-IYDE UNDER ALKALINE CONDITIONS 3 Claims, No Drawings U.S. Cl 8/1 16.3, 260/556,8/115.7 Int. Cl D06m 13/38, D06m 13/14,C07c 13/74 Field of Search 260/556; 8/116.3

References Cited UNITED STATES PATENTS Wagner et a1 Orthner et a1. Bruson et a1. Christiansen...

Hill Dougherty et a1. Sallman et a1.

FOREIGN PATENTS Great Britain Great Britain France France France France Primary Examiner-George F. Lesmes Assistant Examiner-J. Cannon Attorney-Burns, Doane, Swecker and Mathis 260/556 A 260/556A 260/556A 260/556 260/556 260/556 8/116.3 X

ABSTRACT: Formaldehyde is reacted with alkyl sulfonamides under alkaline conditions. The resulting products are useful modification agents for cellulosic fibers.

CROSSLIN KING OF CELLULOSIC MATERIALS WITH PRODUCTS PRODUCED BY THE REACTION OF ALKYL SULFONAMIDES AND FORMALDEIIYDE UNDER ALKALINE CONDITIONS The invention relates to a class of addition products and the use of the same in the cross-linking of cellulosic materials. More particularly, the invention concerns formaldehyde-alkyl .sulfonamide addition products and the use of the same to chemically modify cellulosic fibrous textile products in order to impart improved shape retention thereto.

Within recent years various methods have been devised for treating cellulosic textile products, such as cotton cloth, in order to impart durable wrinkle resistance or better resilience theretoeFor instance, monoand dimethylol derivatives of carboxylic amides and ureas are used extensively for the crosslinking of cotton cellulose, so that easy-care properties are produced. While these and other known cross-linking agents have made a significant contribution to the cotton finishing art, the results have been less than perfect. For instance, in some cases the cross-linking treatment has tended to lack permanency since the finishing agents tend to be gradually removed from the treated article by repeated laundering. In other cases, such treatment substantially impaired theabrasion resistance of the fabric or resulted in objectionable chlorine retention after .hypochlorite bleaching, etc.'For this and similar reasons the industry is continuing its effort to develop new and better finishing agents.

It is an object of the invention to provide a new class of addition products which find outstanding utility in the textile finishing art.

lt is another object of the invention to provide an improved process for imparting easy-care properties to cellulosic materials.

It is a more specific object of the invention to provide a process for imparting easy-care properties to cellulosic fibrous textile products which properties are not significantly diminished after repeated laundering.

A further object is to impart significantly improved wet and dry crease recovery to cellulosic fibrous textile products, with a minimum impairment of their abrasion resistance.

Still another object is to provide a textile finishing process which results in a cellulosic fibrous textile product possessing high moisture regain and which does not discolor, even-after extended periods of use and the accompanying exposure to the atmosphere, bleaching agents, etc.

It is a further object of the invention to provide'a process for enhancing the properties of cellulosic fibrous textile products which may be conducted .with the use of standard textile finishing equipment.

These and other objects, as well as the scope, nature and utilization of the invention will become more clearly apparent from the following description and appended claims.

It has been discovered that a class of addition products which yield outstanding results in textile finishing applications may be produced by the catalyzed reaction of an alkyl sulfonamide and formaldehyde.

The alkyl sulfonamide compounds which may be employed in accordance with the invention may if desired contain a plurality of sulfonamide groups. Illustrative examples of alkyl bissulfonamides which may be utilized are methylene-bismethanesulfonamide, ethylene-bis-methanesulfonamide, l, 3- propane-bis-methanesulfonamide, etc. Alkyl sulfonamides containing a single sulfonamide group per molecule and containing one to about four carbon atoms per alkyl group have been foundparticularly effective in the formation of addition products according to the invention. Illustrative examples of such alkyl sulfonamides are methanesulfonamide, ethanesulfonamide, n-propanesulfonamide, isopropanesulfonamide, nbutanesulfonamide, isobutanesulfonamide, etc. As indicated, the alkyl groups may possess either straight or branched carbon chains. Formaldehyde addition products ofaromatic sulfonamides, such as benzenesulfonamide, p-benzenedi-sulfonamide, p-toluenesulfonamide,-have been produced, but were found to be ineffective as cellulosic cross-linking agents.

The addition products in accordance with the invention may be satisfactorily produced by reacting at least about one mole of formaldehyde with eachmole of the alkyl sulfonamide. A mole ratio of formaldehyde to alkyl sulfonamide of about 2 to l is particularly preferred, and a molar ratio of as high as about 4 to 1 may be utilized, but such additional quantity of formaldehyde fails to produce any further improvement in ultimate cellulose cross-linking properties. The reaction may be conducted at a temperature of between about 0 C. and C. and preferably at a temperature between about 40 C. and 80 C. The reaction is catalyzed by a basic type catalyst, maintaining an alkaline pH, preferably a pH of between about 9 and 11. Illustrative examples of suitable catalysts are the hydroxides and carbonates of alkali metals, such as NaOl-I, KOI-l, Na- CO etc. A reaction time of at least about 60 minutes, and preferably between about 60 and minutes is usually required for the reaction to progress to a sufficient degree of completion.

An aqueous solution containing 10 percent alkyl sulfonamide and an amount of formaldehyde theoretically sufficient to formthe dimethylol product is heated to 50-80 C. for 60 minutes during which the pH is maintained at 10 with suitable base, such.as NaOI-I. After this time the pH is lowered to 3 with dilute acid such as dilute sulfuric acid. Theaddition product is very soluble in water. The reaction can .be run at room temperature foran extended period of time, e .g. 24 hours. The use of 4 moles of formaldehyde per mole of alkyl sulfonamide tends to force the reaction nearer to completion, but the fabrics treated with such a solution are of substantially the same quality as those treated with the solution containing 2 moles of formaldehyde per mole of alkyl sulfonamide.

Basic solutions ofthe cross-linkingcompositions may be stored for considerable periods of. time with no apparent loss in efficiency as a chemical finish.

The exactchemical structure. of the addition product ofthe .alkylsulfonamide and formaldehyde is not known with certainty and its structure is considered to be incapable of simple description or, explanation. There is some evidence,--however, that once a molecule:of the mono or dimethylol derivative of an alkylsulfonamide has formed that it next condenses with either a molecule of unreacted alkyl sulfonamide or with another monomethylol alkyl sulfonamide molecule to produce a more complex product. If it ever be shown that the resulting reaction product results from. both addition and condensation reactions, the product is nevertheless to be considered within the purview of the term addition product" as used;herein. The outstanding .utility of the product as a cellulose cross-linking agent is in no. way dependent upon exact knowledge of its structure or of the complex chemical reactions involved in its formation. Once the cross-linking step has occurred a finished product of exceptional stability is produced.

A satisfactory process for cross-linking cellulose vin accordance with. this invention comprises padding or otherwise wetting the cellulose material with a solution of the alkyl sulfonamide-formaldehyde addition product, drying the impregnated material and curing it by heating under acidic conditions to produce, a treated cellulose possessing improved properties. Cellulose in the form of cotton fabric may be wetted ith an aqueous solution of the addition product, dried, and cured according to standard pad-dry techniques which are well-known in the art. The solution may satisfactorily contain aboutS to 20 percentaddition product by weight. A particularly;preferred solution contains about 10 percent addition product by-weight. An acidic catalyst such as magnesium chloride, zinc nitrate, an aluminum salt, or an'organic and inorganic acid is desirably included in thesolution -in a concentration of from about 10 to 30 percent based on the weight of the addition product-Cure temperatures from about C. to l70C.-'for .a duration of about 2 to l0 minutes are recommended. Particularly outstanding resultsareproduced when a cure temperature of about l50 C. is employedifor about 5 minutes.

The invention is useful for treating cotton yarns and fibers as well as cotton fabric. Also, it is applicable to other cellulosic materials such as viscose rayon, and to fiber blends, for example, blends containing 15 percent to 75 percent cotton EXAMPLES 2-20 in Examples 2 through 20 addition products according to the invention are formed in situ upon 80+80 cotton print cloth, and the mechanical properties of the cross-linked fabric and correspondingly 35 P to 25 Percem f a Synthetic 5 measured. The results obtained are presented in Table [which o o as Polyester nylonr o- A5 be OPVIOUS to follows, together with data obtained from testing a sample of skilled in the art, the cross-linking systems disclosed herein the untreated f b i and Samples f the identical f b i can also be used o "P Paper o the Purpose ofmcreasmg treated with the well known cross-linking agent, dihydroxywet Strength and slmllal propemes- 10 dimethylolethylene urea (DHDMEU). The fabric in Exam- If desired, the addition products according to the invention i 2 2() was dd d i h an aqueous treatin l tion of may be f rm In 1. with an PP P mlxture f the alkyl methanesulfonamide and formaldehyde. Add-ons of about sulfonamide, formaldehyde and catalyst used to wet the cellupercent were hiev d i a h inst n e, The fabri were losic material, dried, and cured at elevated temperatures. dried at 60 C. for minutes and subsequently cured for 5 Under such conditions the addition reaction and the crossmi t t 150C, with the exce tion of the fabric ofExample linking ofthe cellulosic material may be accomplished in a sin- 8 hi h wa dried but received no cure after treatment. All gle operation. fabrics were afterwashed and tumbled dry with the exception When it is desired to produce white goods possessing a of those present in Examples 11 and 16. The afterwash was cross-linked structure it is desirable that any soluble residue of Conducted by in washing in Warm. alkaline Water i h a the alkyl sulfonamide-formaldehyde addition product remain- Conventional neutral. lkyl ary SulfOnaIe detergent d A ing after curing be removed from the treated cellulosic materi- 3 p r nt Concentration of MgCl .6l-l O catalyst was present al prior to the bleaching The removal of such soluble portions n h aqueous t g Solution of E p and a 1 may be accomplished by ordinary laundering or scouring. Percent Concentration of :1)2- 2 catalyst was Bleaching may then be conducted by any standard procedure ployed in Examples 16-20. The aqueous treating solution consuch as the use of a hypochlorite bleach, without resulting in tained 10 percent by weight methanesulfonamide in each exobjectionable chlorine retention. In the prior art, chlorine reample with the exception of TABLE I Molar Degrees equiva lents of Dry crease Wet crease 11 CH 0 recovery recovery Tear Percent Abrasion per mole angle angle Strength moisture (percent of sullonamide (W+F) (W-PF) (W), g. regain untreated) IICllO/N PcrccntN Special conditions Example N0.:

2 1. 0 228 21.0 592 7. (a 3.. 1.0 186 144 800 7. 3 (tired with no catalyst. 4... 1. 0 136 206 576 7. 4 solution, 6..... 1. 5 252 230 544 7. 1

1.5 253 236 528 7.2 Do. 7... 2. 0 270 274 480 7. 2 8..... 2. 0 182 142 800 7. l Dried only, no cure. .l 2. 0 .256 7.1 5% solution. 10.. 2.0 256 7. 5 11.. 2. 0 286 6. 4 Not aftcrwnshcd. 12.. 2.0 .260 l 7 llydrolyzcd at p11 2. 13.. 2.0 272 10.0 llydrolyzcd at 1111 6. l4... 2.0 .262 10.0 ]1 \'(1l'(ll)'Z('(l1lt p11 10. 15.. 2.0 258 9. 0 16 2. 0 208 5 Not nftcrwnslicd. 17.. '2. 0 264 llydrolyzcd nt p11 '2. 18.. 2.0 278 llydrolyzed at 1111 6. 19.. 0 284 llydrolyzed or p11 10. 20 278 1 .1 20lnumlcrings. Untreated contr 170 7. 8 100 DHDMEU trente 302 5.6 48 Single tllltl'WflSll.

Do. 182 ll,\'drol vzvtl at pH 2. Do 250 5.8 2.0 'JOInunderings,

tention of resin treated cellulosic materials has quite often lead to undesirable scorching. The removal of the soluble products present upon the cellulose in no manner detracts from the improved properties resulting from the finishing treatment. In fact, such removal improves the moisture regain of the finished product which produces a further improvement of the hand and enables greater wearing comfort.

The following detailed examples will illustrate the invention:

EXAMPLE 1 To 0.1 mole of methanesulfonamide dissolved in 75 cc. of water is added 0.1 mole of formaldehyde (as 37 percent formalin solution). The pH of the solution is adjusted to 10 by addition of 10 percent NaOH. The solution may be allowed to stand at room temperature for several hours, or may be heated to about 5060 C. for l hour. After this time the pH of the solution is lowered to 3 with dilute HCL. Enough water is added to bring total weight to 100 g. With the addition of the acidic catalyst, the product is ready to use.

To form the 1:1.5 and 1:2 addition product, 0.15 mole and 0.20 mole of formaldehyde respectively are added to the original methanesulfonamide solution.

Examples 4 and 6 which utilized 5 percent methanesulfonamide. The hydrolysis after treatments at various pH values of Examples 12-14 and 17-19 were conducted by (l) soaking fabrics for 30 minutes at C. in a solution containing 1.5 percent phosphoric acid and 5 percent urea at a pH of 2; (2) boiling fabrics in distilled water at a pH of 6 for 30 minutes; (3) soaking fabrics for 30 minutes at 80 C. in a sodium carbonate-bicarbonate buffer solution at a pH of 10. It is believed that the reduction in nitrogen content resulting from hydrolysis may be attributed to the removal of soluble nonbonded dimers, trimers or low molecular weight polymers. The retention of satisfactory wet and dry crease recovery at such exceptionally low nitrogen contents is considered remarkable. The 20 launderings employed in Examples 15 and 20 were conducted by machine washing in warm, alkaline water with a neutral, alkyl aryl sulfonate detergent added.

The fabrics marked DHDMEU" were, for purposes of comparison, padded with a solution containing 15 percent of Permafresh Reactant 183 (a solution of dihydroxydimethylolethyleneurea marketed by Sun Chemical Corp.) and 2.7 percent of a solution of Catalyst X-4 (a solution of zinc nitrate). Fabrics were dried for 10 minutes at 60 C., cured for 5 minutes at C., afterwashed, and tumble dried.

EXAMPLES 21-26 In Examples 21 through 26 as reported in Table 11 results obtained according to the invention utilizing a wide variety of alkyl sulfonamides to cross-link a cellulosic material are reported. in each instance the addition products were formed in situ upon 80 80 cotton pring cloth, and the mechanical properties measured. The fabrics were padded with aqueous TABLE II Molar equiva- Degrees lents of HCHO Drycrease Wet crease per mole recovery recovery Tear Percent Example sullonaangle angle strength moisture No. Compound mlde (W-i-F) (W+F) (W), g. regain IICHO/N 21. N-methylmethanesulfonamide 1.0 160 22 Methylene-bismethanesu1fonamide 2. 240 23 1,S-propane-bismethanesulfonamide. 2. 0 240 24. Ethanesulionamide 2. 0 200 25 n-Butanesulfonamide 2. O 256 26... N-(methanesullonyl)-glycine 2. 0 249 As has been indicated, the present invention provides a class of addition products, and a process for significantly improving mechanical properties of cellulose fibers utilizing the same. High dry and wet crease recovery angles are achieved. A somewhat greater resistance to abrasion than found in common commercial finishes is produced. Treated fabrics possess a high moisture regain (7-10percent) as compared to a moisture regain of about percent in common finished goods. Wash-wear ratings of 4 to 5 commonly result. White fabrics retain their whiteness after long periods of use, and fabrics possess the outstanding attribute of being capable to withstand repeated commercial laundering without a significant diminution of the resulting enhanced properties as is a common result with many of the prior art processes.

Although the invention has been described in connection with preferred embodiments, it is to be understood that varia- 1. A process for cross-linking a cotton-containing fabric which comprises:

impregnating the fabric with a treating solution containing 5 to 20 percent by weight of an addition product of formaldehyde and a sulfonamide selected from the group consisting of methane sulfonamide and ethane sulfonamide, said product being formed by heating an aqueous solution containing 1 to 4 moles of formaldehyde per mole of sulfonamide at a pH between about 9 and 1 l and at a temperature between about 40 and C. for from about 60 to about minutes; drying the resulting impregnated material; heating the dried material at a temperature between about and C. for from about 2 to 10 minutes in the presence of an acidic curing catalyst to produce a fabric possessing improved shape retention properties; and washing residual water soluble addition product from the fabric, thereby minimizing subsequent chlorine retention. 2. A-process according to claim 1 wherein said sulfonamide is methane sulfonamide.

3. A process according to claim 1 wherein the sulfonamide is ethane sulfonamide. 

2. A process according to claim 1 wherein said sulfonamide is methane sulfonamide.
 3. A process according to claim 1 wherein the sulfonamide is ethane sulfonamide. 